1. Field of the Invention
This invention relates generally to enclosures housing electrical apparatus and more particularly to such enclosures that include access doors that are sealed by interlocks when the apparatus is energized.
2. Background Information
Medium voltage motor control equipment (2,300V to 7,200V) typically include a mechanical interlock to prevent entry into a medium voltage motor starter without first de-energizing or shutting down the power to the starter circuit. The standards for this type of equipment do, however, allow for this mechanical interlock to be bypassed if certain conditions are met. For example, at times it is desirable to have access to the contactor, isolation switch, fuses, etc., which are contained behind the medium voltage control equipment housing door, for the purpose of taking infrared pictures of these components while the starter is energized. These pictures permit engineering analysis of potential problem areas where "hot" spots or overheating can at times occur. Correcting these problem areas before they cause damage can save money on equipment and maintenance costs, as well as prevent hazardous conditions from developing that can otherwise affect the personnel handling the equipment. Accordingly, it would be desirable to provide controlled access to the components within the housing while the equipment is operating. It is also desirable to provide such access in a manner that would not permit the interior of the housing to be exposed inadvertently while the equipment is activated.